The invention is directed to a wall saw, in particular a wall saw for making flush cuts in concrete and the like substrates, in accordance with the preamble of patent claim 1. The invention is also directed to a saw blade for use in combination with a wall saw of the type mentioned above in accordance with the preamble of patent claim 8.
Wall saw systems are arrangements for cutting through walls of reinforced or unreinforced concrete with the aid of rotating saw blades provided with cutting segments and are described, for example, in brochure Nos. W 1881 594 10-d, 1994 and W 1838 993 10-d, 1993, published by the Hilti Aktiengesellschaft. They are used in building construction above, at or below ground level in, building demolition and renovation. For example, in demolition work for redevelopment projects, building modifications, or erection of add-on structures, it may be necessary to cut through or demolish existing concrete walls or to cut out areas of the concrete walls. In many applications, cuts can be made in areas of the concrete walls where there is adequate distance from an adjacent wall, ceiling or floor; on the other hand, flush cutting is required especially when making cuts for add-on structures or when cutting out door openings and the like. This means, for instance, that the cut must be made flush with an adjacent, vertically extending wall or, in the case of cutting out door openings, that the cuts must run flush with the floor and with the ceiling.
Conventional fastening arrangements which fix the saw blade to the saw head or saw arm cannot be used for flush cut applications of this kind because such arrangements are composed of elements that are arranged on both flat sides of the saw blade so as to clamp the saw blade between them and connect it with a drive unit mounted at the saw head. The fastening elements project over the flat sides of the saw blade and thus render flush cutting impossible. Flush flanges, as they are called, which are fixedly connected with the drive unit at the saw head or saw arm were developed for this reason. The saw blade is fixedly connected with the flush flange with the aid of countersink screws which are inserted through bore holes in the saw blade from the side located opposite to the flange and screwed into the flange. The heads of the screws terminate flush with the flat side of the saw blade. In these known flush flanges, no fastening elements project over the free flat side of the saw blade and cutting can accordingly be carried out flush with an adjacent wall, floor or ceiling.
When using wall saws and especially in flush cutting applications, care must be taken not to work with the largest saw blade diameter right from the start irrespective of the required or desired depth of cut. This is principally because saw blades with very large diameters of up to 1600 mm, for instance, can be deformed axially during operation, particularly under axial loading. This can cause vibrations or oscillations in the saw blade during operation and impair the true or circular running of the saw blade. Also, in flush cutting applications only one side of the saw blade is guided by the flush cut flange at the start of the cutting process. Therefore, the problem of oscillations in the saw blade can be even more pronounced in flush cutting applications. Therefore, when using wall saws a saw blade with a smaller starting diameter of 600 mm or 700 mm, for example, is always mounted to begin with for producing a preliminary cut. Subsequently, the saw blade is exchanged for a saw blade of greater diameter one or more times in gradations of 200 mm to 300 mm in order to produce a cut of the required depth. The saw blades with greater diameters are guided on both sides in the cut which has already been made and can thus no longer be deformed axially.
In the known fastening arrangements and flush cut flanges, the exchanging of saw blades is relatively time-consuming and difficult to manage, since the saw blade must be completely separated from the fastening arrangements. Flush cut applications have the additional problem that the fastening screws can only be reached from the flat side of the saw blade which faces the adjacent wall, floor or ceiling. For this reason, it is often necessary to lift the saw head from the track or running rail along which it is longitudinally displaceable and to tilt it in order to loosen the fastening screws, of which there are six, for example. After lifting off the saw blade from the flush cut flange connected with the saw head or saw arm, the next largest size saw blade must be lifted up and placed on the flush cut flange. The saw blade can only be secured to the flush cut flange again by the fastening screws after bringing the bore holes in the saw blade in alignment with the bore holes in the flush cut flange. The saw head with the saw blade secured thereto must then be attached to the running rail again.
It is relatively cumbersome and time-consuming to change the saw blades. In addition, it should not be forgotten that a saw head weighs about 30 kg or more and the saw blades weigh up to 70 kg. Therefore, in order to lift the saw head from the running rail and replace it on the running rail, the user must lift and adjust a weight of 100 kg. It should be taken into consideration that this must also be carried out under very cramped conditions in flush cutting applications. The saw blade is heavy and--especially with large diameters--very bulky and difficult to handle and can only be lifted with difficulty. Therefore, with known fastening arrangements for the saw blades and especially in known flush cutting flanges, changing saw blades also always requires a relatively great physical effort on the part of the user.
Therefore, it is an object of the present invention to improve a wall saw in such a way that the saw blade can be changed simply and quickly. It should be possible, even under cramped conditions such as occur particularly in flush cutting applications, to change the saw blade without needing to lift it from the running rail and tilt it. In general, the user should not have to lift the saw blade in order to change it. The saw blade should also be prepared in such a way that the saw blade can be lifted more easily than was previously possible should it ever be necessary to do so, e.g., in order to remove an exchanged saw blade from the work area.